1. Field Of The Invention
The present invention relates to chromatographic analyzers. More specifically, the present invention relates to a solvent wash and process stream valving system for a chromatographic analyzer.
2. Description Of The Prior Art
The use of chromatographic analyzers in process control involves the determination of the concentration of constituents in a sample fluid. The sample fluid to be analyzed is introduced into an analyzer column containing a selective constituent partitioning material. A carrier gas is also directed into the column to force the sample material therethrough. In order to provide for liquid samples containing soluble nonvolitile constituents which upon vaporization of liquid sample can become deposited in the sample valve and connecting fluid lines of the chromatographic analyzers, suspended particulates and heat produced polymeric residues which result in plugged lines and valves, the use of a solvent wash technique to clean the valve and the lines using a wash solvent was developed. The solvent wash liquid is passed through the sampling, i.e., valving and fluid conduit zone after the sample to be analyzed and the carrier gas is passed through the sampling zone. A typical prior art solvent apparatus in a chromatographic analyzer is shown in U.S. Pat. No. 3,372,573. However, in such a prior art solvent wash system, the process stream containing the samples to be analyzed continually flows through the sample valve which is located in the heated analyzer oven. The application of heat to that sampled stream often results in a continual deposition of solid material, e.g., polymeric residue inside the sample valve as well as the sample line located inside the oven. Further, the prior art solvent wash systems do not provide for exclusion of solvent leakage into the chromatographic column.